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BUG: KCSAN: data-race in do_mpage_readpage / set_blocksize

write to 0xffff888102202b86 of 1 bytes by task 3098 on cpu 0:
 set_blocksize+0x21f/0x2b0 fs/block_dev.c:153
 sb_set_blocksize fs/block_dev.c:163 [inline]
 sb_min_blocksize+0xa3/0x120 fs/block_dev.c:179
 fat_fill_super+0xd5d/0x2a00 fs/fat/inode.c:1649
 vfat_fill_super+0x2c/0x40 fs/fat/namei_vfat.c:1050
 mount_bdev+0x1e2/0x280 fs/super.c:1419
 vfat_mount+0x2d/0x40 fs/fat/namei_vfat.c:1057
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4a/0x190 fs/super.c:1549
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x1269/0x1c00 fs/namespace.c:3203
 do_mount fs/namespace.c:3216 [inline]
 __do_sys_mount fs/namespace.c:3424 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3401
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3401
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888102202b86 of 1 bytes by task 3099 on cpu 1:
 do_mpage_readpage+0x6c/0x1030 fs/mpage.c:160
 mpage_readahead+0x157/0x340 fs/mpage.c:391
 blkdev_readahead+0x18/0x20 fs/block_dev.c:637
 read_pages+0xa0/0x6e0 mm/readahead.c:130
 page_cache_ra_unbounded+0x464/0x4c0 mm/readahead.c:238
 do_page_cache_ra mm/readahead.c:267 [inline]
 force_page_cache_ra+0x226/0x260 mm/readahead.c:298
 page_cache_sync_ra+0x194/0x1c0 mm/readahead.c:572
 page_cache_sync_readahead include/linux/pagemap.h:839 [inline]
 generic_file_buffered_read+0x38d/0x2110 mm/filemap.c:2227
 generic_file_read_iter+0x80/0x3d0 mm/filemap.c:2535
 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1925
 call_read_iter include/linux/fs.h:1881 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x56d/0x5e0 fs/read_write.c:481
 ksys_read+0xce/0x180 fs/read_write.c:615
 __do_sys_read fs/read_write.c:625 [inline]
 __se_sys_read fs/read_write.c:623 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:623
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3099 Comm: systemd-udevd Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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